The general field to which this invention most closely relates is the field of flow measurement by measurement of the rate of heat transfer from a hot body to the moving fluid. Previously known in this field are instruments known as hot-wire anemometers which are composed of thin wires of silver-platinum or tungsten which are disposed in the fluid flow. These instruments tend to be very fragile due to the small wire diameters ordinarily employed and further tend to have great calibration problems due to a number of factors including deposition of dust particles on the wire. Shielded hot-wire anemometers have also been proposed in which the hot-wire is enclosed within a cylindrical sleeve to reduce the effect of dust deposition and to provide greater mechanical strength for the instrument at the expense of decreased sensitivity. Because the rate of cooling of these apparatuses is dependent upon the fluid temperature, inaccurate results are obtained unless the fluid temperature is either controlled or measured. Due to the difficulties in calibration of these instruments, it is difficult to construct a temperature measuring instrument having the tracking temperature characteristics in order to provide a correction for the fluid temperature.